Piercing die and alloy



Patented Oct. 19, 1943 PIERCING DIE AND ALLOY William F. Finkl, Chicago,Ill., assignor to A.

Finkl & Sons Company, Chicago, 111., a corporation of Illinois NoDrawing. Application March 25, 1942, r Serial No. 436,183

4 Claims. (Cl. 75126) This invention r'elatefs'to improvements in steelalloys which are adapted for use in piercing dies used with hot workdies, and particularly for punches, plungers, inserts and plugs orsimilar die members of relatively small section made of .such alloy, andused in'hot work forging processes under high temperature conditions.

The principal object of'the invention is to pro-, ducea steel alloy diepart combining the special characteristics which have been found to beessential to theuses 'above .set forth, including facility and economyof manufacture, and in particular the capability of holding its workinghardness at extremely high. temperatures and having a greater resistanceto breakage than other alloys previously used for similar purposes.

The improved alloy has been developed to overcome the difficulties ofbreakage and excessive wear which have been encountered with punches andplungers and similar small-sectioned die parts used with hot work dies.Such die parts are subjected to the most rigorous and exactingconditions because of the extreme variations in temperaturesencountered. These small-sectioned die parts must remain in contact withthe work at extremely high temperatures for relatively long periods oftime, and are usually cooled as by water between uccessive operations.

Several types of steel alloys have heretofore been employed for theparticular purposes above mentioned, of which tungsten-bearing alloysare especially notable. It has been found, however, that none of theseprior alloy steels arewholly satisfactory since the small-sectioned dieparts such as punches, plungers, inserts andthe like are usually thefirst parts to break or: show wear in dies of this general character.Moreover, such -alloy teels, particularly those containing tungsten,have been "found relatively costly to manufacture, and the virtues oftungsten itself as an" alloying element are more than oifset by anundesirable brittleness after working a short time at relatively hightemperatures.

' In carrying out my present invention for the particular purposes aboveindicated, I utilize molybdenum, chromium, silicon and manganese, allconfined within relatively narrow ranges. The preferred ranges of theprincipal alloying elements of this special steel are as follows:

Per cent Carbon .25 to .35 Molybdenum 2.00 to 2.50 Chromium 4.50 to 5.00Silicon .80 to 1.00 .20 to .40

Manganese Other elements of a more or less residual char- As an exampleof a steel alloy made in accordance with my present invention, thefollowing anyalysis may be cited:

Per cent Carbon .30 Molybdenum 2.00 Chromium 5.00

Silicon 1.00 Manganese .35

It will be observed from the above analysis that the carbon content isrelatively low (.25 to .35) as compared with steelalloys heretoforegenerally employed for hot die work, whereas both the molybdenum andchromium contents are rela-- tively high as compared with molybdenum andchromium alloys such as broadly disclosed in my prior Patent No.1,464,174. I find that the addition of a relatively substantial fractionof silicon (.80 to 1.00%) also adds to the desired wearresistingpropertie at the high temperatures of the steels these die parts areused to form.

The special characteristics essential for superior performance inpunches, plungers, inserts, plugs and similar small-sectioned die parts,particularly those used for piercing in extrudin punches and forplungers on upsettingv machines, can be obtained to a high degree bylimiting the percentages of the several alloying elements within thenarrowranges specified for each. Such small-sectioned die parts can beinitially manufactured and handled for heat treatment and machined muchmore economically and safely than tungsten-bearing and similar specialalloys heretofore employed for like purposes. Die parts made of my alloyare capable of holding their hardness at extremely high temperatures andcan withstand water cooling during the time they are operated, with muchless likelihood of breakage.

l have found that in practice under most severe shown an averageproduction greatly in excess of acter such as nickel may'also be presentin small I fractions, as is often the case in special alloy steels ofthis class.

that obtained from dies having similar parts made of specialtungsten-bearing alloy of the kind heretofore generally employed forthis special purpose.

I claim as my invention:

1. A steel alloy which comprises as its alloying elements carbon rangingfrom .25 to 35%, molybdenum from 2.00 to 2.50%, chromium from 4.50 to5.00%, silicon from .80 to.1.00%, manganese from .20 to .40%, and thebalance substantially all iron.

2. A steel alloy which comprises as its alloying elements carbonapproximately 30%, molybdenum approximately 2.00%, chromiumapproximately 5.00%, silicon approximately 1.00%, manganeseapproximately 35%, and the balance substantially all iron.

3. A piercing die for hot work forging made of a steel alloy whichcomprises as its alloying el e v ments carbon ranging from .2 5to'.35%,molyb-- denum from 2.00 to 2.50%; chromium 1rom 4.50"- to 5.00%silicon irom'.80 to 1.00%, manganese? from .20 to .40%, all iron.

4. A piercing .di

and the halance substantially v e m not work forzin inadestantiallyallirpn. r

